Is there a link between vitamin K2 and weight gain?
Research indicates that there is no evidence to support the claim that vitamin K2 causes weight gain. In fact, the scientific findings point in the opposite direction. Several human and animal studies have explored the relationship between vitamin K2 status and body weight or fat composition, with some suggesting a protective or even reductive effect on body fat, especially visceral fat. The idea that this vitamin might be a culprit for unwanted pounds is unfounded, and instead, its metabolic role appears to be a favorable one.
The surprising truth: K2 and fat reduction
One of the most notable studies on this topic was a 3-year, randomized, placebo-controlled trial involving 214 postmenopausal women. The participants were given either 180 mcg/day of vitamin K2 (MK-7) or a placebo. While supplementation had no effect on the overall body composition of the entire group, a subgroup of 'good responders'—women with a strong increase in circulating carboxylated osteocalcin—experienced a significant decrease in abdominal fat mass and visceral adipose tissue compared to the placebo group. Visceral fat is the harmful type of fat stored around abdominal organs, making this a particularly significant finding.
Animal research has also provided compelling support for K2's role in body composition. A three-month study on mice fed a high-fat diet found that those also supplemented with vitamin K2 gained less weight and body fat than the control group. These findings, while preliminary and based on animal models, suggest a potential mechanism where K2 enhances fat degradation.
How vitamin K2 influences metabolism
Vitamin K2 does not cause weight gain because its metabolic pathways are centered on enhancing, not hindering, your body's efficiency. Its primary functions involve activating proteins that regulate calcium, but it also has downstream effects on metabolic processes.
- Enhancing fat metabolism: Vitamin K2 may influence genes related to fat metabolism, such as those involved in fatty acid oxidation. This process involves breaking down fatty acids for energy, which could potentially reduce fat storage. Studies on animal models have shown that K2 can enhance fat degradation.
- Improving insulin sensitivity: Research has linked higher vitamin K2 status with better insulin sensitivity and glucose metabolism. Improved insulin sensitivity helps regulate blood sugar and how the body stores fat, which is a key component of healthy weight management. This is also linked to an increase in adiponectin, a hormone that regulates glucose levels and fatty acid breakdown.
- Synergy with vitamin D3: The relationship between vitamin D3 and K2 is often discussed in the context of bone health, but it also has implications for weight. Vitamin D3 assists with calcium absorption, while K2 directs that calcium to where it's needed (bones and teeth) and away from soft tissues like arteries. A healthier cardiovascular system allows for more consistent physical activity, indirectly supporting weight loss efforts.
Important food sources of vitamin K2
There are two primary forms of vitamin K: K1 and K2. Vitamin K1 is found in leafy green vegetables, while vitamin K2 is found in fermented foods and animal products. Getting adequate K2 often requires focusing on these specific dietary sources.
- Natto: A traditional Japanese fermented soybean dish, natto is by far the richest dietary source of K2 (specifically MK-7).
- Dairy: Certain cheeses, particularly aged and hard cheeses like Gouda and some soft cheeses, are good sources of vitamin K2.
- Organ Meats: Goose liver and beef liver contain significant amounts of K2.
- Eggs: Egg yolks contain vitamin K2, with the exact amount varying depending on the hen's diet.
- Other Animal Products: Salami, chicken, and other meats also contribute to K2 intake.
The complete picture: K1 vs. K2
| Feature | Vitamin K1 (Phylloquinone) | Vitamin K2 (Menaquinone) |
|---|---|---|
| Primary Source | Leafy green vegetables (spinach, kale, broccoli) | Fermented foods (natto, cheese) and animal products (organ meats) |
| Main Function | Primarily involved in blood clotting | Crucial for calcium regulation, bone health, and heart health |
| Distribution in Body | Concentrated in the liver | Wider distribution in soft tissues (brain, bones, arteries) |
| Weight Impact | No direct evidence of impact | Emerging evidence suggests link to reduced fat and better metabolic health |
| Recommended Intake | Standard recommendations focus on K1 for clotting function | No official daily value, but higher intake associated with metabolic benefits |
Is supplementation necessary?
While dietary sources are ideal, supplements can be useful, especially for those with low intake of K2-rich foods or specific health goals. When taking K2 supplements, it's often recommended to pair them with vitamin D3, as they work together synergistically. It is important to note that dietary supplements are not a magic solution for weight loss and must be combined with a healthy diet and regular exercise for optimal results. Consult a healthcare provider before starting any new supplement regimen, especially if you take blood-thinning medication.
Conclusion
Based on current research, the concern that can vitamin K2 cause weight gain is directly contradicted by available evidence. The data from both human and animal studies suggests that vitamin K2 has a neutral or potentially positive effect on body composition, possibly aiding in the reduction of abdominal and visceral fat through improved metabolic functions. This occurs through complex mechanisms involving fat degradation and enhanced insulin sensitivity, rather than being a direct weight loss tool. While a holistic approach to weight management remains key, ensuring adequate vitamin K2 intake—either through food or supplementation—can be a supportive part of a healthy lifestyle.
Sources
- Knapen, M.H.J., Braam, L.A.J.M., Drummen, N.E. et al. Vitamin K-induced effects on body fat and weight: results from a 3-year vitamin K2 intervention study. Eur J Clin Nutr 72, 136–141 (2018). https://doi.org/10.1038/ejcn.2017.146
- He Ma, et al. The Impact of Vitamin K2 (Menaquionones) in Children’s Health and... Nutrients. 2022 Jan 5;14(1):215. doi: 10.3390/nu14010215. PMID: 35010647; PMCID: PMC8774117.
